Electrical signaling.



R. A. FESSENDEN. ELECTRICAL SIGNALING. APPLICATION FILED DEC. 23, 1907.

1 ,OO2,052. Pa ztented Aug. 29, 1911.

UNITED sTATEsrA'rEn'r orrrcn.

REGINALD A. FESSENDEN, OF BRANT ROCK, MASSACHUSETTS, ASSIGN OR TO NATIONAL ELECTRIC SIGNALING COMIANY, OF PITTSBURG, PENNSYLVANIA, A CORPORATION OF NEW JERSEY.

ELECTRICAL SIGNALING.

Specification of Letters Patent.

Application filed December 23, 1907. Serial No. 407,749.

1 To all whom it may concern:

- siding at Brant Rock, in the county of Plymouth, State of Massachusetts, have invented certain new and useful Improvements in Electrical Signaling, of which improvements the following is a specification.

My invention' relates to telephone transmitters.

In the accompanying drawings forming a part of this specification Figure 1 shows an arrangement of apparatus suitable for carrying out the invention, where the trans mitter is actuated directly by the voice"and Fig. 2 a suitable arrangement where the transmitter is actuated by an electro-magnet.

The invention herein disclosed has for its object the securing of greater efficiency in the production of electrical impulses by means of slight changes of pressure, whether produced directly or indirectly by .sound waves or by any other means.

When certain classes of substances, for example silicon and tellurium, are used to form one element of a contact and are brought into perfect non-microphonic contact with another conductor, such as brass, the contacts so formed are capable of acting either thermoelectrically or as rectifiers, according to the amount of-pressure used, and where a local battery is also used, according to the intensity'of local battery used. With the majority of these substances the thermoelectric current produced is in the opposite direction to the current produced by the rectifying action. The writer has discovered that a sensitive telephone transm'itter may be constructed by using such a contact and suitably adjusting the pressure, and, where a local battery'is used, suitably adjusting the current from the local battery.

In Fig. 1, His the diaphragm of a telephone transmitter attached to which is a small conducting rod 12, which maybe of brass, the outer end of which is preferably rounded. The outer end of the rod 12 rests against a button 13 .which may beofsilicon, said button being fastened to the brass disk 14. The brass disk. 14 is mounted on the flexible arm 15, and the pressure between. 13 and 12 is adjustable bymeans of the screw 16.

17- is a local battery adjustable by means of the sliding contact 22.

18 is the secondary of a' transformer whose primary 20 is connected to a high frequency alternator 19.

21 is a telephone receiver.

On suitably adjusting the transmitter, and talking into the mouthpiece so as to set the diaphragm 11 into vibration, and'thus vary the pressure between 13 and 12, the speech is reproduced in the receiver 21.

I do not limit myself to the employment of a single contact as more than one contact may be used.

In Fig. 2 the diaphragm 11 instead of being actuated directly by the voice is actuated by the current in the circuit 26, 24, 24', 27, where the pressure is adjusted by means of the screw 23 and the silicon button 13 is placed on the diaphragm, with the brass rod 12 pressing against it. The high frequency alternator and transformer shown in Fig. 1 are omitted, not being essential. On signals being transmitted through the circuit 26, 24, 24', 27 they are rendered audible in the receiver 21.

By the term self responsive contact is meant a contact which, having its opposite elements connected to an indicating mechanism without any local battery being in the circuit, will produce an indication when a high frequency current is caused to pass through the contact.

Patented Ang.29,1911.

composed of an element of high specific resistance and with thermoelectric power, devices for passing a current through said contact, and an indicating instrument in c1rcuit operated by changes of current due to the action of the thermo-couple, substantially as described. 3. A transmitter comprising a pair of terminals in good contact composed of material to generate ourfor electric signa i g" rent, a vibrator connected with one of said terminals, means to pass a current throughthe contact, and an indicating instrument erated in the contact.

4:. A telephone transmitter comprising. a

.pair of mechanically separate electrodes of different materials in good or non-microphonic contact, and adaptedby characteristics of the members, to respond automatically to variations of pressure between them.

5. A telephone transmitter comprising a thermo-couple of separate electrodes in nonmicrophonic contact, means to vary the pressure in accordance with sound waves and an indicating instrument operated b changes of current strength in a circuit inc uding the thermo-couple. 1

In testimony whereof I have hereunder signed my name in the presence of the subscribed witnesses.

REGINALD A. .FESSENDEN.

Witnesses JEssm E. BE T," J. W. LEE. 

